Environmental requirements:

Sexes:

The majority of Rigellians bore a strong physical resemblance to Humans. The species also had a warrior elite known as the Kaylar who were specially bred for generations and subsequently appeared very different to the average Rigellian, generally being much larger and having fang-like teeth. (EVcomic: "Our Dearest Blood")

The Rigellians were historically a warlike race, which eventually matured into xenophobia, with the race shying away from being part of the galactic community and being actively hostile when they did have contact with aliens, which for a long time made Rigel VII one of the most feared planets in its sector.

However, by the 23rd century, and following first contact with the Federation, much of Rigellian society came to see their history as barbaric. They moved to reform their society, with the aim of bringing it into line with Federation standards and hoping to join the larger galactic community as a Federation member world. These reforms included the disbanding of the Kaylar, a controversial policy which incited a strong reaction from traditionalists. This culminated in a conspiracy that reached high into the Rigellian government and led to a Kaylar coup on the eve of Rigel's entry into the Federation and the day of the last Kaylar parade in the Rigellian Festival of Light. This resulted in Rigel VII not becoming a Federation member world in 2254. (EVcomic: "Our Dearest Blood")

The incident shocked much of Rigellian society, spurring them to continue their reformations. It was suspected that Rigel VII could quite possibly reclaim its place in the Federation. (EVcomic: "Nor Iron Bars a Cage")